Need Help from you Experts Please!!!

Hello There!

I was wondering if someone can help me out. I have now missed my period for 5 days, and have been having cramps for the last 5 days as well. On my lower stomach and back. I have also been having diharrea and my boobs are very sore as well. I have taken two HPT's but both have came back negative. I am not sure when I should take the next test? Is there a possibilty of pregnancy? I would really appreciate your help!! Thank you!